Roger Federer, right, stands with coach Severin Luthi during a practice session ahead of the Australian Open in Melbourne, Australia, on Friday.

MELBOURNE, Australia — Novak Djokovic and Roger Federer witnessed Andy Murray’s drought-breaking successes after he hired Ivan Lendl as coach, and decided they were due for an overhaul of a major kind.

Both took on past Grand Slam champions ahead of the Australian Open, with Djokovic recruiting Boris Becker to help him try to win a fourth straight title in Melbourne and Federer working out a part-time deal with Stefan Edberg.

“It’s great to see other legends of the sport coming back and trying to help the active tennis players during their careers,” Djokovic said at Friday’s draw. Federer said he’d like to see even more tennis greats bringing their experience back to the tour.

Murray stuck with the eight-time major winner, Lendl — a partnership that has so far yielded titles at the U.S. Open and Olympics in 2012, and at Wimbledon last year.

The top ranked players haven’t yet followed the trend for celebrity coaches, though.

Rafael Nadal tried some new therapies on his knees in the offseason but otherwise has an unchanged team led by his uncle Toni, who has guided his career since childhood. It was good enough to win him 10 titles last year and regain the No. 1 ranking after a seven-month absence from the tour.

Serena Williams sought a little bit of extra guidance from a tried and trusted source closer to home this time around, spending time in the offseason with her father, Richard Williams, in Florida to fine-tune parts of her game.

“My dad has always been, for me, my greatest coach and the best coach ever,” Williams said. “He knows when to step back. He knows when to say `Yeah.’ He knows when to be like, `Ok, this girl is nuts — I’m not going to say anything right now!’

“He knows me better than anybody else.”

Before her 2013 season, Williams worked out in Mauritius with Patrick Mouratoglou’s group. After an upset loss in the quarterfinals at Melbourne Park to Sloane Stephens, she rebounded to win 78 of her 82 matches last season.

After opening 2014 with a successful title defense in Brisbane, with Mouratoglou still in the stands, Williams is confident she can end Victoria Azarenka’s two-year reign at Melbourne Park.

Even in Brisbane, where she had back-to-back wins over Azarenka and Maria Sharapova, two of her biggest rivals, Williams was getting pointers long-distance from her dad.

“He knew what I needed to do. He’s like `Serena, you’re not doing A, B, and C, this isn’t what we worked on.”’

She won’t get a chance to play Sharapova and Azarenka back-to-back in Melbourne, with both on the opposite side of the draw.

“It was a great test. It showed me where my level was,” she said. “I’m happy I was able to play both Maria and Victoria, because they brought their A games against me.

“I know now what I need to do for Melbourne.”

Williams, who hasn’t lost a competitive match since August, starts her Australian Open campaign against Australian teenager Ashleigh Barty, and has 2011 U.S. Open champion Sam Stosur and two-time Australian finalist Li Na in her half of the draw.

Critics have questioned whether Williams can top her achievements of 2013. She won 11 titles, including two majors, became the oldest player to be No. 1 and spent all but seven weeks atop the rankings.

“I had a similar question in 2012. I had such a good year winning two Slams and a gold ... I just didn’t think I could do better,” she said. “Arguably I may have done better, so I’m just going to be up for that challenge again.”

Azarenka and Sharapova — coming back after playing just one post-Wimbledon match in 2013 due to hip and shoulder injuries — could meet in the semifinals.

Azarenka has a potential fourth-round match against Stephens, who had an upset win over Serena Williams in the quarterfinals last year. Stephens withdrew from the Hopman Cup with a left wrist problem, but is expected to be fit for the season’s first major.

Sharapova was content with her run to the semifinals in Brisbane in her first tournament back from injury. She has been working with Sven Groenefeld as coach. Her first-round match is against Bethanie Mattek-Sands.

Of the “Big Four” men, three are on a loaded top half of the draw.

Nadal, who won the Qatar Open to start his season, opens against Australia’s Bernard Tomic and has Murray and Federer in his half. He could meet No. 5-ranked Juan Martin del Potro, the 2009 U.S. Open champion, in the quarterfinals.

Murray lost in the second round at Doha last week, his first tournament since minor back surgery in late September. Federer reached the final at Brisbane, where he lost to another 32-year-old former No. 1, Lleyton Hewitt.

Djokovic has what appears to be an easier path to the final, but Becker has already advised him that there’s no such thing as an easy draw at a Grand Slam.

“Boris brings (a) new, fresh approach,” Djokovic said. “He is a true legend of our sport ... and his experience will help me win new trophies.”

Djokovic is aiming to be the first man in the Open era to win five Australian titles.

He was in peak form at the end of last season, finishing on a 24-match winning streak after losing the U.S. Open final to Nadal.

With Murray saying it would be “unrealistic” for him to be considered a top contender for the Australian title, and 17-time major winner Federer saying he probably wouldn’t be back in peak form until March or April, Nadal looms as the main obstacle to Djokovic’s fourth straight Australian title.

He missed the 2013 edition due to injury, so his last match at Melbourne Park was a 5-hour, 53-minute, five-set defeat of Djokovic in the 2012 final.

It has been a decade since Federer won his first Australian title — something he commemorated with a fundraising exhibition match in front of 14,000 fans on Rod Laver Arena this week.

After slipping out of the year-end top five for the first time since 2002 and winning just one title, Federer realized he needed a fresh approach. So he called in Edberg, one of his childhood idols, to help out.

“I trained probably harder than all the guys ranked ahead of me in the offseason,” Federer said. “I really feel I’m on my way back. Who knows? Maybe I’m playing my very best in March or April is my feeling.